rocket stove in crawl space

Posts: 2

posted 8 years ago

I am currently using a kerosene heater in the crawl space under my house to keep my pipes from freezing. The pipes were not installed below frost level (they are 2' deep and frost line is 4') I would like to replace the kerosene heat with a rocket heater. But constraints on clearances and also poor winter construction conditions have ruled out a masonry box (too big, too heavy, too hard to heat cure). So I created a steal design based on the book designs. My unit would be all-steel, welded construction. From my understanding, the main goal is to achieve a complete burn in the riser. If I have read correctly in the forum, I have two main concerns:

1. maintaining enough heat in the riser

2. having enough turbulence to cause complete combustion air mix.

As a function of design for limited dimensions, I would have to limit the exterior of the exhaust chamber to 15" or so. Instead of vermiculite or some other lose fill, I'd need to use some kind of 1" ceramic wool around the 7" square riser, but don't know if AEW is good enough, or should I go with something rated higher.

My other quandary has to do with thickness of steal for various sections of the burn chamber and other chambers. I was thinking 1/2" plate for the riser, but this is going to make the entire project about 300 pounds! Would a 1/4" plate be workable without too much loss for oxidation and also would this be enough to reflect enough heat with the 1" insulation?

Would packing the exhaust pipe run with earth (dirt) scrub off enough heat? Would it store heat nearly as well as urbanite? I cannot do a permanent installation at this point, so it has to come out again.

If lack of turbulence is a problem with a steel riser, would it be possible to weld some kind of steal baffles into the riser that would create turbulence? I am thinking of something like the baffles in a clothes dryer that help tumble the clothes. Or would this create to much back pressure?

I'm just registered today. Had the book for about a month and have read it several times. As I'm not living in said house and thus have no internet at the moment, my replies will be slow, but I hope this gives some food for thought. I hope to have a .pdf of design available if that helps you in critiquing and adds to the knowledge base.

Posts: 2

posted 8 years ago

I forgot to mention that I've design the exhaust shroud (the barrel replacement) to be detachable at the based for inspection of the riser. This will give me the ability to monitor how quickly conditions degrade. Also, I plan to line the floor above the burn chamber with aluminum sheeting, as I have done with my kerosene heater. This is very effective in keeping the floor temp far from critical (currently it's at about 70 F).

Posts: 29

posted 8 years ago

3/16" in my opinion would be ok and if i could i'd use hot rolled steel, it's more stable